Method for controlling an internal combustion engine

Abstract

The previous ignition timing is used as a starting point for repititive ignition cycles to define the primary coil current flow starting point, in order to secure a sufficient current flow duration for the primary coil current that is supplied to an ignition coil to thereby prevent a shortage of ignition energy. An arithmetic circuit including a central processor produces data representing the duration between the previous ignition timing and the primary coil current flow starting point. A counter starts this counting operation from the previous ignition timing. The primary coil current feed to the ignition coil starts at a time when the contents of the counter are coincident with the result of the processor produced data. The data is obtained by subtracting a necessary primary current flow duration or time from the interval between the previous ignition timing and the present ignition timing.

What is claimed is: 
     
       1. A method of operating a processor-controlled apparatus for controlling the operation of a combustion engine, said engine including an output shaft driven by mechanical energy converted from heat energy caused by the combustion of fuel, said engine including a source of electrical energy, ignition means, coupled with said source, for cyclically storing energy supplied from said source and discharging energy to be employed for combustion of fuel, detecting means, coupled to said engine output shaft, for producing a reference signal in response to a predetermined angle of rotation of the engine output shaft, and sensor means for producing signals representative of operational conditions of the engine, said method comprising, for each cycle of operation of said ignition means, the steps of: (a) generating a first signal in response to which said ignition means begins the storage of energy from said source and causing said ignition means to store energy for a prescribed charging duration, and     (b) generating a second signal in response to which said ignition means discharges energy stored thereby so as to cause the combustion of fuel in said engine, the time interval from the generation of said second signal to the generation of said first signal corresponding to a predetermined period of time that energy is not being stored by said ignition means, and wherein step (b) comprises the step of:     (b1) in response to a reference signal from said detecting means, generating first data, the value of which is successively changed from a first prescribed value until the value of said first data corresponds to a value representative of the time at which said second signal is to be generated, and thereupon causing the generation of said second signal, and   wherein step (a) comprises the step of (a1) in response to the value of said first data corresponding to the value representative of the time at which said second signal is to be generated in step (b), generating second data the value of which is successively changed until the value of said second data corresponds to a value representative of the time at which said first signal is to be generated, and thereupon causing the generation of said first signal,     and wherein, for successive cycles of storage and discharge of energy by said ignition means, step (a) further comprises the step of (a2) generating the value representative of the time at which said first signal is to be generated by: (a2-1) generating third data representative of the interval between the time of occurrence of said second signal for a present cycle and the time of occurrence of said second signal for the previous cycle,   (a2-2) generating fourth data representative of said prescribed charging duration, and   (a2-3) generating fifth data representative of the time interval from the generation of said second signal to the generation of said first signal in accordance with the difference between said third and fourth data,       and wherein step (a1) comprises the step of (a1-1) generating said first signal in response to the value of said second data becoming equal to or greater than the value of said fifth data.     
     
     
       2. A method according to claim 1, wherein step (a2-1) comprises the steps of (a2-1-1) generating sixth data representative of the interval between successive reference signals produced by said detecting means,   (a2-1-2) generating seventh data representative of the difference between the value of the present first data at the time at which the present second signal is to be generated and the value of the previous first data at the time at which the previous second signal was generated, and   (a2-1-3) combining said sixth and seventh data in accordance with a prescribed relationship to obtain said third data.   
     
     
       3. A method according to claim 2, wherein step (a2-1-3) comprises combining said sixth and seventh data in accordance with the relationship: said third data=said sixth data±said seventh data.   
     
     
       4. A method according to claim 1, wherein step (a2-2) comprises the steps of (a2-2-1) generating sixth data representative of the magnitude of the voltage of said source of electrical energy, and   (a2-2-2) generating said fourth data in accordance with a prescribed relationship between said fourth data and said sixth data.   
     
     
       5. A method according to claim 4, wherein step (a2-2-2) comprises the steps of: (a2-2-2-1) comparing said sixth data with seventh data, said seventh data being reference data representative of a predetermined voltage,   (a2-2-2-2) generating eighth data representative of a proportionality constant, the value of which corresponds to a first predetermined constant in response to said sixth data being less than said seventh data, and the value of which corresponds to a second predetermined constant in response to said sixth data being larger than said seventh data,   (a2-2-2-3) generating ninth data representative of the difference between said sixth data and said seventh data,   (a2-2-2-4) generating tenth data representative of the product of said eighth data and said ninth data,   (a2-2-2-5) generating said fourth data by arithmetically combining said tenth data with eleventh data, said eleventh data being representative of a prescribed reference time interval during which said ignition means stores energy from said source.   
     
     
       6. A method according to claim 5, wherein step (a2) further comprises the steps of (a2-4) comparing said fifth data with twelfth data which corresponds to a preestablished reference interval of time during which energy is discharged by said ignition means for the combustion of fuel, and   (a2-5) changing the value of the fifth data generated in step (a2-3) to said twelfth data upon the value of said fifth data being less than that of said twelfth data, whereby, in step (a1-1) said first signal is generated in response to the value of said second data becoming equal to or greater than the value of said twelfth data.   
     
     
       7. A method of operating a processor-controlled apparatus for controlling the operation of a combustion engine, said engine including an output shaft driven by mechanical energy converted from heat energy caused by the combustion of fuel, said engine including a source of electrical energy, ignition means, coupled with said source for cyclically storing energy supplied from said source and discharging energy to be employed for ignition of fuel, detecting means, coupled to said engine output shaft, for producing reference signals in response to a first predetermined angle of rotation of said engine output shaft and position signals in response to a second predetermined angle of rotation of the engine output shaft, and sensor means for producing signals representative of operational conditions of the engine, said method comprising, for each cycle of operation of said ignition means, the steps of: (a) generating a first signal in response to which said ignition means begins the storage of energy from said source and causing said ignition means to store energy for a prescribed charging duration, and   (b) generating a second signal in response to which said ignition means discharges energy stored therein so as to cause the combustion of fuel in said engine, the time interval from the generation of said second signal to the generation of said first signal corresponding to a predetermined period of time that energy is not being stored by said ignition means,     wherein step (b) comprises the step of: (b1) in response to a reference signal from said detecting means, generating first data the value of which is successively changed from a first prescribed value in accordance with said position signals produced by said detecting means until the value of said first data corresponds to a value representative of the time at which said second signal is to be generated and thereupon causing the generation of said second signal, and     wherein step (a) comprises the steps of (a1) in response to the value of said first data corresponding to the value representative of the time at which said second signal is to be generated in step (b), generating second data the value of which is successively changed in accordance with said position signals produced by said detecting means until the value of said second data corresponds to a value representative of the time at which said first signal is to be generated, and thereupon causing the generation of said first signal,     and wherein, for successive cycles of storage and discharge of energy of said ignition means, step (a) further comprises the step of (a2) generating the value representative of the time at which said first signal is to be generated by: (a2-1) generating third data representative of the number of position signals that have been produced between the time of occurrence of said second signal for the present cycle and the time of occurrence of said second signal for the previous cycle,   (a2-2) generating fourth data representative of the number of position pulses corresponding to said prescribed charging duration, and   (a2-3) generating fifth data corresponding to the difference between said third data and said fourth data, said prescribed charging duration being established in accordance with the resulting value of said fifth data.       
     
     
       8. A method of operating a processor-controlled apparatus for controlling the operation of a combustion engine, said engine including an output shaft driven by mechanical energy converted from heat energy caused by the combustion of fuel, said engine including a source of electrical energy, ignition means, coupled with said source, for cyclically storing energy supplied from said source and discharging energy to be employed for the combustion of fuel in accordance with control signals applied thereto, detecting means, coupled to said engine output shaft, for producing a reference signal in response to a predetermined angle of rotation of the engine output shaft, and sensor means for producing signals representative of operational conditions of the engine in response to which processor-based control signals are generated for controlling said ignition means, said method comprising, for a respective cycle of operation of said ignition means, the steps of: (a) generating a first control signal in response to which said ignition means begins the storage of energy from said source and causing said ignition means to store energy for a prescribed charging duration, and   (b) generating a second control signal in response to which said ignition means discharges energy stored thereby so as to cause the combustion of fuel in said engine, the time interval from the generation of said second control signal to the generation of said first control signal corresponding to a predetermined period of time that energy is not being stored by said ignition means,     and wherein step (a) comprises the steps of: (a1) generating a first data signal representative of the interval between the time of occurrence of the second control signal for the previous ignition cycle and the time of occurrence of the second control signal generated for the present ignition cycle, relative to the rotation of the engine output shaft;   (a2) generating a second data signal representative of said prescribed charging duration for the present ignition cycle in accordance with operational conditions of the engine, and   (a3) generating said first control signal in accordance with a prescribed relationship between said first and second data signals.     
     
     
       9. A method according to claim 8, wherein said prescribed relationship is defined in accordance with the difference between said first and second data signals. 
     
     
       10. A method according to claim 8, wherein said detection means includes means for producing position pulses in response to a prescribed angle of rotation of the engine output shaft less than that for which said reference signals are produced, and wherein said second data signal generated in step (a2) is generated in response to the production of position pulses by said detection means. 
     
     
       11. A method according to claim 8, wherein said sensor means includes means for generating an output representative of the operational state of said electrical energy source and wherein said second data signal is generated in step (a2) in accordance with said output. 
     
     
       12. A method according to claim 8, wherein step (b) comprises the steps of: (b1) generating a third data signal the value of which is successively changed until the value of said third data signal reaches a predetermined value and thereupon generating a first output signal, and   (b2) in response to said first output signal, generating a fourth data signal the value of which is successively changed until the value of said fourth data signal reaches a prescribed value and thereupon generating said second control signal.   
     
     
       13. A method according to claim 12, wherein said detection means includes means for producing position pulses in response to a prescribed angle of rotation of the engine output shaft less than that for which said reference signals are produced, and wherein the values of said third and fourth data signals are successively changed in response to the production of said position pulses. 
     
     
       14. A method according to claim 13, wherein said sensor means includes means for generating an output representative of the operational state of said electrical energy source and wherein said second data signal is generated in step (a2) in accordance with said output. 
     
     
       15. A method according to claim 12, wherein said apparatus further comprises means for supplying a sequence of clock pulses, and wherein the values of said third and fourth data signals are successively changed in response to said clock pulses. 
     
     
       16. A method according to claim 15, wherein said first control signal is defined in accordance with the period of said clock pulses. 
     
     
       17. A method according to claim 12, wherein said sensor means includes means for generating an output representative of the operational state of said electrical energy source and wherein said second data signal is generated in step (a2) in accordance with said output. 
     
     
       18. A method according to claim 15, wherein said clock pulses are produced in accordance with the rotation of said engine output shaft. 
     
     
       19. A method according to claim 15, wherein said clock pulses are produced from a clock source separate from said engine output shaft. 
     
     
       20. A method according claim 11, wherein step (a2) comprises the steps of (a2-1) comparing said output to a prescribed reference value representative of a predetermined output of said electrical energy source,   (a2-2) generating a charging duration correction signal in accordance with a prescribed function the value of which varies in dependence upon the difference between said output and said prescribed reference value and whether or not said prescribed reference value is no greater than or exceeds said reference value,   (a2-3) generating said second data signal in accordance with said charging duration correction signal.